This invention relates to the automated assembly of semiconductor devices, and particularly to an assembly process using two lead frames.
Lead frames are known in the semiconductor industry and, typically, are used in the fabrication of integrated circuits. Although the lead frames used according to the present invention differ from known lead frames, as hereinafter disclosed, known lead frame fabrication techniques and materials can be used in the practice of the present invention, hence the term "lead frame" is herein adopted.
The present invention has particular utility in the fabrication of semiconductor rectifiers of the type comprising a semiconductor chip having top and bottom surfaces, an anode terminal connected to one of the chip surfaces and a cathode terminal connected to the other chip surface. Each terminal extends laterally beyond the surface to which it is attached and has a portion bent to extend along a side of the chip to a mid-plane of the chip and then laterally away from the chip in such mid-plane. A complete semiconductor rectifier includes a housing, e.g., of a molded resin, completely encapsulating the chip and substantially all of the anode and cathode terminals with the exception of portions of the terminals which extend laterally outwardly from the device housing and provide means for electrically connecting to and mounting the device. The terminals extend in opposite directions from the device in a common plane.
An advantage of the in-plane arrangement of the terminals is that it facilitates mounting of the rectifier on a printed circuit board. For example, the rectifier can be machine inserted into an opening through a printed circuit board and automatically seated therein with the in-plane terminals pressed against a surface of the circuit board. By means of pre-applied solder layers, the terminals are then bonded to printed circuit paths on the circuit board which underlie and are contacted by the terminals.
Heretofore, rectifiers of the type described have been assembled more or less manually, e.g., by successively disposing one terminal, the chip and then the other terminal into proper positioned and contacting relationship within a jig, and then simultaneously soldering together the device parts.
The present invention is concerned with automated fabrication of semiconductor devices, and particularly to the fabrication of rectifier devices of the type described.